Is there a command or flag to clone the user/group ownership and permissions on a file from another file? To make the perms and ownership exactly those of another file?
On GNU/Linux chown
and chmod
have a --reference
option
chown --reference=otherfile thisfile
chmod --reference=otherfile thisfile
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1Could you reference to this answer (and likely cite it) as answer to my question : unix.stackexchange.com/questions/44253/… ? , I think I will be great addition and I'd love to find up-votes there for it. – Grzegorz Wierzowiecki Jul 31 '12 at 20:40
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@GrzegorzWierzowiecki: probably that question should be closed, but is a little bit different than this and already has answers, so I better do nothing. – enzotib Jul 31 '12 at 20:54
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As you wish and suggest. Thanks for help, I have never put attention to
--reference
parameter ofchmod
andchown
before :). – Grzegorz Wierzowiecki Jul 31 '12 at 22:02
On any unix with GNU utilities, such as (non-embedded) Linux or Cygwin, you can use chmod --reference
and chown --reference
.
If your system has ACLs, try the ACL commands getfacl
and setfacl
. These commands differ a little from system to system, but on many you can use getfacl other_file | setfacl -bnM - file_to_change
to copy the permissions. This doesn't copy the ownership; you can do that with careful parsing of ls -l other_file
, assuming that you don't have user or group names containing whitespace.
LC_ALL=C ls -l other_file | {
read -r permissions links user group stuff;
chown -- "$user:$group" file_to_change
}
getfacl other_file | setfacl -bnM - file_to_change
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1
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2@enzotib At least on Linux, ACL tools will work to copy permissions (but not ownership) even if the source and target filesystem don't support ACLs. – Gilles 'SO- stop being evil' Sep 14 '11 at 6:57
Did a bash command based on the response of Matteo :)
Code:
chmod $( stat -f '%p' "$1" ) "${@:2}"
Usage:
cp-permissions <from> <to>...
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6Egad! Where did you learn to say
${*:2}
? Don't ever do that again! That will fail if any of the filenames contain space (or tabs). Use"${@:2}"
. Also, use"$1"
instead of just$1
. – G-Man Says 'Reinstate Monica' May 26 '15 at 4:10 -
chmod "$(stat -c '%a' "$fromfile")" tofile
in GNU Coreutils, but you might as well use--reference
in that case since thestat
CLI utility is not POSIX, it even says pubs.opengroup.org/onlinepubs/9699919799/utilities/ls.htmlthatls -l
won't cut it: "The output of ls (with the -l and related options) contains information that logically could be used by utilities such as chmod and touch to restore files to a known state. However, this information is presented in a format that cannot be used directly by those utilities or be easily translated into a format that can be used." – Ciro Santilli新疆棉花TRUMP BAN BAD Sep 2 '18 at 12:10
If you are not using a system with GNU's chmod/chown (which support the --reference
option) you could try to parse the output of ls -l
Here a small script for chmod
(if you have a see which supports extended regexes they could be written in a much more readable way ...)
#!/bin/sh
reference=$1
shift
files=$*
# strip the permissions (whith extended regexes could be more readable)
OWNER=$(ls -l ${reference} | sed -e "s/.\(...\).*/\1/" | sed -e "s/[-]//g" )
GROUP=$(ls -l ${reference} | sed -e "s/....\(...\).*/\1/" | sed -e "s/[-]//g" )
OTHER=$(ls -l ${reference} | sed -e "s/.......\(...\).*/\1/" | sed -e "s/[-]//g" )
chmod u=${OWNER},g=${GROUP},o=${OTHER} ${files}
UPDATE:
This is even easier using stat
:
chmod $( stat -f '%p' ${reference} ) ${files}
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2
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@jfgagne: thanks makes sense I do not know why I didn't think about it in the first place. I updated the answer – Matteo Sep 22 '11 at 5:28
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1You're using *BSD
stat
syntax here. Yourchmod $(stat ...)
command won't work because%p
alone outputs too much information for *BSD'schmod
, use%Lp
to output just the u/g/o bits. Something slightly more elaborate would be required for sticky/setuid/setgid bits. – mr.spuratic Jun 7 '13 at 10:17
I wanted to add an adjustment to Matteo's script. A for loop should be used to validate that the files exist before actually running the chmod command on them. This will let the script error out more gracefully.
I think this is the best option because it can be used for all *nix OSes, like Solaris, Linux, etc.
#!/bin/sh
reference=$1
shift
files=$*
for file in $reference $files; do
[ -f $file ] || { echo "$file does not exist"; exit 1; }
done
# strip the permissions (whith extended regexes could be more readable)
OWNER=$(ls -l ${reference} | sed -e "s/.\(...\).*/\1/" | sed -e "s/[-]//g" )
GROUP=$(ls -l ${reference} | sed -e "s/....\(...\).*/\1/" | sed -e "s/[-]//g" )
OTHER=$(ls -l ${reference} | sed -e "s/.......\(...\).*/\1/" | sed -e "s/[-]//g" )
chmod u=${OWNER},g=${GROUP},o=${OTHER} ${files}
I found that on one of my Solaris 10 machines, stat
was not found. That might be an issue with my configuration though.